Technical Field
The present invention relates to a fuel tank system.
Related Art
Fuel tank systems with a valve member (diaphragm valve) provided in a vent pipe for transporting gas inside a fuel tank to a canister are known (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2013-117181). In such fuel tank systems, ordinarily a valve member is placed in a closed state by causing the internal pressure of the tank to act on a back pressure chamber of a valve member, and hermetically close the fuel tank. When necessary, the valve member is placed in an open state by opening the back pressure chamber of the valve member to the atmosphere, and gas inside the fuel tank is transported to the canister. Moreover, in such a fuel tank system, a full tank limit valve provided with a float that floats on the liquid fuel inside the fuel tank is provided at an end portion of the vent pipe on the fuel tank side.
In such a fuel tank system, gas flows vigorously from the fuel tank and into the vent pipe when the back pressure chamber of the valve member is opened to the atmosphere and the valve member is opened in a state of excessively high tank internal pressure inside the fuel tank. The flow of gas acts on the float of the full tank limit valve, and there is a risk that the full tank limit valve might be closed. If the full tank limit valve is closed then gas inside the fuel tank cannot be transported to the canister side, meaning that fueling and pressure release cannot be performed.